In the early 1930s, at a point when Salvador Dalí was still very firmly placed within the Surrealists’ encampment, the Catalan artist devised a stunt—theorists writing now would, using the vocabulary of contemporary performance art, call it a “happening” or an “action”—involving giant baguettes. The idea was to bake huge loaves (special ovens would need to be constructed for the purpose) and deposit them in various spots around Paris. A 15-metre baguette was destined for the gardens of the Palais Royal, a bigger one for Versailles and so on; eventually, in some doughy culmination, a massive 45-metre loaf would appear, as mysteriously as its Parisian counterparts, on the streets of New York.

Dalí’s baguette work was a trick, as Dawn Ades, art historian and curator of the Palazzo Grassi’s monumental Dalí exhibition that opens on 12 September, readily admits. “But”, she stresses, “there was also an elaborate idea underlying this”. Indeed there was: surreal placement, often with a wildly exaggerated dimension—here, in the very enormity of the loaf—was directly linked to a larger idea of subverting the workings of the rational world. It was far from being an absurdist gesture devoid of depth and context; to read Dalí’s own analysis of the prank is to apprehend the political, philosophical, even moral, detail with which he imbued his work. (In the event, Dalí’s baguettes stunt went unperformed.)

But theoretical considerations of misplaced loaves of bread aside, Dalí’s idea (it does not actually matter that it existed only as an unexecuted plan) had an auxiliary effect, the significance of which goes to the heart of much post-war art. As an extravagant gesture, it accentuated a public persona that he had, even by that time, already spent years deliberately cultivating. Dalí was confusing the figure of the artist with that of the work of art, a tendency that Professor Ades relates directly to the work of Duchamp, the dadaist with whom Dalí shared a close friendship. Even allowing for the flamboyant grandstanding of many of his Dada and Surrealist contemporaries, Dalí—as the studied embodiment of eccentricity—stood head and shoulders above the rest.

From the vantage point of retrospection, this elision, with all its performative implications, seems like the essence of modernity. An admixture of art, advertising, media and celebrity culture has meant that, increasingly, the figure of the artist has become synonymous with his work. Obvious points of reference include Andy Warhol, Gilbert & George and Tracey Emin, whose work is often filled with intimate details of her life. Other artists have used their own bodies as an equivalent of a jumping-off point into further territories: Matthew Barney (via his epic “Cremaster” film cycle) and Orlan (with her endless surgical transformations) suggest that the artist’s body is something that is in a state of continuous transition and remodelling. Anxiety around such constant flux is a tendency that the young Canadian artist Dana Wyse exploits to its full sardonic (and comic) potential: her late-1990s series “Pills and Powders” look like vitamin sachets. On closer inspection, the description panels on Wyse’s little bags promise transformations that verge on the magical: “Believe in God”; “Instant German accent”; “Guarantee the heterosexuality of your child”; and, best of all, “Understand contemporary art instantly”. This, suggests Elisabeth Lebovici, the art critic for the French newspaper Libération, is a new development: by turning the art object into an effect, we move closer to the Popism of Warhol et al, “where the increase of consumer goods led to an increase in the consumption of images”.

But given that this collapse of categories is not so new, it is remarkable that a degree of confusion still surrounds fundamental questions: At what point does an artist become inseparable from the work that he or she makes? Is the figure of the artist an integral aspect of the work? Does celebrity enhance the work at hand or merely distract attention?

To an extent, the value of such questions lies in the issues they flag rather than their answerability. And certainly in the case of Dalí, it is apt, in the centenary year of his birth, that Professor Ades is addressing these issues head on. She recognises that the general presence of Dalí in the media—exacerbated by woefully unwitty pastiches of his work, from melting-clock watches to Lego kits depicting a moustachioed artist by his lobster telephone and unimpressive museums such as London’s Dalí Universe—contributes little to any profound appraisal of him.

To counter this, the Palazzo Grassi’s centenary exhibition (alongside Ades’s lavishly illustrated catalogue) is very much a major, and definitive, show that, while not ignoring the importance of Dalí’s public persona, focuses primarily on his art and thought. The product of a formal collaboration between numerous bodies, but pre-eminently, the Gala-Salvador Dalí Foundation in Figueras and the Venetian museum, the show features over 200 canvases, some of which—such as “Women lying on a beach” (1926)—have not been exhibited since they disappeared into private collections decades ago. Other canvases, like the large-scale “Neo-Cubist academy” (1926) and the “Madonna of Port Lligat” (1950), are travelling from locations as diverse as a monastery in Monserrat and the Fukuaka Art Museum on the Japanese island of Kyushu respectively. (Next year, the exhibition travels to its sole American venue, the Philadelphia Museum of Art.)

Professor Ades aims to rehabilitate Dalí as one of the great epic painters and artistic thinkers of his generation. “Dalí was, undoubtedly, a showman”, she says, “but he was also a fantastic painter. We must never lose sight of that. His gestures tend to be part of lively ideas that inform the paintings”.

As she notes, the history of much contemporary art, from Dada and Surrealism to Fluxus and the Brit Art of the last decade, is characterised by the porous boundaries between practice and works of art. Sometimes artists exploit them, smudging the boundary lines completely, and so the question of where public art ends and a private individual begins is difficult to answer with any degree of relative certainty. “There are no clear answers to be given”, says Professor Ades. “There was a performative aspect to his work and it is very easy to construct Dalí as a showman. The danger with this is that not enough attention is then paid to the ideas that lie behind spectacular stunts. The baguettes episode is one example; another is the incident which involved him throwing a bathtub through a shop window in New York City [in 1939]. This was interpreted as an artistic gesture; in fact, he had been cross with the way the store had meddled with an installation he had made. He shoved the tub back into its original position…” And the tub, closely followed by Dalí, crashed through the glass of the New York department store, Bonwitt-Teller. (That Dalí was briefly arrested on charges of criminal damage complicated matters further.)

But public acclaim and critical appraisal are not the same thing. It is interesting that as the former increased (especially after Dalí’s wartime stay in New York), the latter decreased. The reasons for this are complex, and certainly the surrealist break with Dalí, as well as the artist’s ambiguous politics, both play a part in the process. But examples of the reductio that comes when unchecked acclaim runs riot are easily found.

Take, for example, what happened when Tracey Emin lost her cat, Docket, earlier this year. Emin’s reaction was nothing out of the ordinary. She made some A4 reward notices with Docket’s picture on them, photocopied them and stuck them up on various surfaces within her east London neighbourhood. As people realised that it was Emin’s cat that was missing (and therefore that the posters were manufactured by her), the A4 sheets themselves disappeared. Soon they were being offered for sale for £500 on eBay. The whereabouts of Docket’s posters became headline news and White Cube, Emin’s gallery, was compelled to issue a terse statement explaining that the poster was “not a conceptual piece of work and it has nothing to do with her art”. (Incidentally, Docket was found, alive and untouched by his encounter with celebrity, by a historian who lives nearby.)

The late critic, Daniel Farson, provides a similar cautionary tale in A portrait, his 1999 biography of Gilbert & George. He describes what happened when he assembled a panel of critics for Gallery, a BBC radio discussion programme on art. “I noticed that when we showed a Bacon or a Sickert, the panellists would talk about the painting”, Farson wrote. “Shown a G&G, they concentrated on G&G themselves”.

Resorting to the ad hominem is, unhappily, predictable. Yet it is also unhelpful to any greater understanding of the work and any analysis of the performance of the artist in making the work. In the case of Gilbert & George, where the two men present themselves very much as a single entity that is itself as much part of their oeuvre as their huge, signature “stained-glass” paintings, the separation is made doubly difficult. (In interview, they avoid anything other than the most cursory discussion of topics that predate the creation of Gilbert & George.) Logic tells us that the two suited men are the fabricators of the pictures on the wall; it takes a level of sophistication to see that Gilbert & George are also the creations of an Italian and an Englishman who happen to be called Gilbert and George.

In curating the Palazzo Grassi retrospective, Professor Ades is aware of such pitfalls, but she underlines that Dalí’s theatrical self-presentations does not divert attention from his very real talents and significance. “I am trying to show Dalí in terms of a fantastic painter who went on being so—even in the post-war period, something which is often overlooked. Dalí was a painter and an ideas man. He was both”, she stresses. “Above all, what I am hoping to do is create a situation where, when Dalí is mentioned, people think of the painter, and not the man with the moustache”.

Dawn Ades, “Dalí: the centenary retrospective” (Thames & Hudson), is published on 11 October, £45. “Dalí” is at Palazzo Grassi, Venice (12 September to 9 January 2005); it travels to the Philadelphia Museum of Art (16 February to 15 May 2005).